Persistence of the anti-cholinesterase soman in rats; antagonism with a non-toxic simulator of this organophosphate.

Anaesthetized, atropinized rats were poisoned with 6x LD50 soman (1,2,2,-trimethylpropyl methylphosphonofluoridate). Purified acetylcholinesterase, injected i.v. 75 min later, was rapidly inhibited, presumably by soman stored in a 'depot' from which it was gradually released. Existence of a depot is supported by the effect of a soman-simulator ('som-sim'), an organophosphonate structurally similar to soman but devoid of anti-cholinesterase activity. Som-sim can expel soman from the depot, or counteract its formation. Som-sim prophylaxis greatly enhances survival.